Magnetostriction of Ytterbium and Cerium in YIG

Abstract

Measurements using strain gauges of the magnetostriction constants of Yb³⁺ and Ce³⁺ ions in YIG are presented. The temperature dependence of the magnetostriction for Yb³⁺ in YIG is compared to theories by Callen and Callen based on crystal‐field (single‐ion) and anisotropic rare‐earth‐iron‐exchange (two‐ion) interactions. The measured temperature dependence of the magnetostriction for Yb³⁺ in YIG agrees closely with that predicted from the anisotropic exchange interaction. The measured temperature dependence of the magnetostriction of Ce³⁺ in YIG is difficult to interpret in terms of the two interactions because, in contrast to Yb³⁺, the sublattice magnetization cannot be evaluated analytically since the energy‐level scheme of the rare‐earth ground state is not completely determined and the higher levels of the ground state become populated at temperatures where the two interactions could be distinguished. The results are consistent with a ground‐state exchange splitting of Ce³⁺ in YIG of ∼200 cm⁻¹. Recent paramagnetic‐resonance staticstrain measurements of Phillips and White are discussed.